Study On Preparation Of Ti-coated Electrode And Its Application In Degradation Of Nitrobenzene In Wastewater

A series of Ti-coated electrodes (also known as Dimensionally Stable Anodes, DSA electrodes) are prepared which were modified by doping Pd, Co, Si and introducing Sn-Sb intermediate-layer into the RuO2/Ti electrode, in order to enhance the electrochemical properties and service-life of the electrode. These modified electrodes are used as anodes in electro-catalytic reactor to degrade Nitrobenzene (NB) which is difficult to be biochemical degraded. The optimum technological parameters of wastewater treatment with different DSA electrodes as anodes are ascertained. The basic theory and applied research in electro-chemical properties and organics removal efficiencies are carried out, which can provide technical supports to the further application of electro-catalytic technology in wastewater treatment field.The modified electrodes of Sn-Sb/Ti, Ru-Pd/Ti,Ru-Pd-Co/Ti,Ru-Si/Ti are prepared. By investigating coats micro-morphology, electro-chemical properties, brushing mole concentration, stability, NB removal efficiencies of different electrodes, ascertaining the coats sintering temperatures respectively are 500℃,450℃,400℃,500℃; the coats component ratios respectively are n(Sn):n(Sb)=7.2:1, n(Ru):n(Pd)=0.65:1, n(Ru):n(Pd): n(Co)=0.65:1:0.71, n(Ru):n(Si)=7:3; the brush times of electrodes respectively are 15,24,21, 21.The RuO2/Ti electrode is modified by different ways when the three elements of Pd, Co, Si are doped. This modification can differently affect the electro-chemical properties and service-life of electrodes. It's demonstrated that the modified electrodes have better electro-chemical properties and longer service-life than RuO2/Ti electrode through electro-chemical properties tests and NB degradation experiments.The electrodes of Ru-Pd/Sn-Sb/Ti, Ru-Pd-Co/Sn-Sb/Ti, Ru-Si/Sn-Sb/Ti are prepared when Sn-Sb intermediate-layers are introduced into the modified electrodes. Keeping the intermediate-layer brush time is 5, each modified electrodes can get longest service-life when the surface-layer brush times respectively are 18,21,21. It's ascerntained that the electro-chemical properties and service-life can be further improved, and the NB removal efficiencies can be enhanced when Sn-Sb intermediate-layers are introduced.Through wastewater treatment experiments, the optimum technological parameters of react time, current density, electrolytes concentration, original pH, plates distance are ascertained. It's demonstrated that the experiment system is suitable for high concentration organics wastewater treatment. Na2SO4 is more suitable as support electrolyte than NaCl for this electro-catalytic oxidation system. It's beneficial to enhance NB removal efficiencies and TOC removal efficiencies when Sn-Sb intermediate-layers are introduced. This electro-catalytic oxidation system can partly mineralize pollutants into H2O and CO2 in wastewater. The NB and TOC degradation status of different electrodes respectively are as follows:②Sn-Sb/Ti electrode:ENB>90%, Eoc>80%;②Ru-Pd/Sn-Sb/Ti electrode:ENB> 90%, ETOC>50%;③Ru-Pd-Co/Sn-Sb/Ti electrode:ENB>85%, EToc>50%;④Ru-Si/Sn-Sb/Ti electrode:ENB>S0%, ETOC>50%.By investigating the NB degradation process, it's indicated that the electro-chemical degradation process is ascribed to the synergistic effects of anode and cathode both, not only the existence of the anode oxidation, but also the reduction of cathode. In this electro-catalytic oxidation system, the NB degradation was according with the first order kinetics equation.